Large constriction of lattice constant in epitaxial magnesium oxide thin film: Effect of point defects on lattice constant

Epitaxial thin films prepared using an MgO target on silicon substrate often show constriction of lattice constant (a∼4.1 Å). Detailed investigation of the crystal structure excluded the possibility that the epitaxial films are either cubic spinel MgO or magnesium silicate (a/2∼4.1 Å). With such a constriction in rock salt MgO structure point defects must be induced into structure. An ab initio method with semicore pseudopotentials predicted such constrictions on configurations of Schottky type defects. The Schottky defects with random distribution throughout lattice cites satisfied constricted lattice constant, mass density, and crystallography experimentally observed on the epitaxial MgO films.